I would think a bad sensor circuit would bring up one of the Oil pressure circuit codes I mentioned , too... That is why I am inclined to think you do not have a problem. I wish I could find a pressure/resistance chart so you could just ohm the thing out , but I looked through all my manuals and Benz does not give that chart and their test in the CD is to hook up a mechanical gauge for verification
Do you ever see a dip in pressure at idle on a hot day and high coolant temps ??